The present invention relates to a powder inhaler and a method of constructing the same. More particularly, the present invention relates to a powder inhaler having a reduced number of component parts as compared to known powder inhalers, which powder inhaler is hence easier to construct than known powder inhalers.
A number of powder inhalers are known which use different systems for introducing a dose of powder into an air stream. Typically, the powder is inhaled into the lungs of a patient in order to treat, for example, asthma.
FIG. 1 illustrates such a powder inhaler. The inhaler comprises a mouthpiece 2 comprising an air chamber (not illustrated) and an outlet nozzle 4, an inhaler body 6 and a rotatable grip portion 8 for operating a dosing mechanism for providing doses of powder for inhalation. The inhaler body 6 is provided with an opening 10 which is filled with a window 12 through which an indicating wheel 42 is visible so as to provide an indication as to the usage of the inhaler.
FIG. 2 illustrates in exploded view component parts disposed within and to the inhaler body 6. The inhaler body 6 is capped with a divider 14 which is fixed thereto and separates the air chamber in the mouthpiece 2 from a major part of the inhaler body 6. For aesthetic reasons the inhaler body 6 is an opaque moulding. The divider 14 is a transparent moulding which has a depending tongue 15, a part of which forms the window 12.) When the inhaler is assembled, the only part of the divider 14 which is visible is the part of the tongue 15 forming the window 12, and thus the overall appearance of the inhaler is unaffected.
Within the inhaler body 6 are housed the component parts of the dosing mechanism. These component parts include a dosing unit 16 which comprises a plurality of dosing means 18 and has a central axial shaft 20, an inhalation unit 22 which comprises an inhalation channel 24 and a storage unit 26 which comprises a storage chamber 28 for storing powder. The above-mentioned component parts of the dosing mechanism are assembled by passing the inhalation channel 24 through an opening 30 in the storage unit 26 and passing the shaft through central openings 32, 34 in the inhalation unit 22 and the storage unit 26 respectively. When so assembled, the upper ends of the inhalation channel 24 and the storage chamber 28 pass respectively through first and second openings 36, 38 in the divider 14.
In use, powder is transferred from the storage chamber 28 to one of the dosing means 18, and, with rotation of the dosing unit 16, the one dosing means 18 provides a dose of powder to the inhalation channel 24. On inhalation by a user the powder is drawn up through the air chamber and out of the outlet nozzle 4 of the mouthpiece 2.
As illustrated in FIGS. 2 and 3, the divider 14 further comprises supporting means 40 for rotatably supporting an indicating wheel 42. The indicating wheel 42 has a plurality of teeth 44 disposed around the periphery thereof which engage with a spiral groove or protrusion 46 on the end face of the shaft 20 of the dosing unit 16. The supporting means 40 is configured to align the indicating wheel 42 such that a part of the periphery thereof is disposed adjacent the inner surface of the window 12.
In use, as the dosing unit 16 is rotated, the spiral groove or protrusion 46 engages with one or more of the teeth 44 on the indicating wheel 42 so as to rotate the same. In this way, by providing a coloured marking on the periphery of the indicating wheel 42, it is possible to provide the user with a visible indication at the window 12 as to the usage of the inhaler.
Although the above-described known powder inhaler functions quite adequately, its construction is relatively complicated and it is formed from a large number of component parts. It is thus an aim of the present invention to provide a powder inhaler which has a fewer number of component parts and is of simpler construction.
Accordingly, the present invention provides an inhaler for administering powder by inhalation, comprising: an inhaler body having an opening therein; an indicating wheel disposed in the inhaler body for providing an indication as to the usage of the inhaler, the indicating wheel being disposed such that at least part thereof is visible through the opening and so as to be rotatable in a diametrical plane containing the central axis of the inhaler body; a divider substantially closing one end of the inhaler body; and a storage unit disposed in the inhaler body, the storage unit comprising a storage chamber for storing powder for inhalation; wherein that the inhaler body and the divider are formed as a single integral unit of an opaque material and in that the storage unit is formed of a transparent material and has a portion which substantially fills the opening.
Embodiments of this aspect of the invention may include one or more of the following features.
Preferably, the inhaler further comprises an inhalation unit disposed in the inhaler body, the inhalation unit having an inhalation channel through which powder is in use inhaled. In a preferred embodiment the inhalation unit and the storage unit are formed as a single integral unit.
Preferably, the inhaler further comprises a dosing unit disposed in the inhaler body so as to be rotatable about the central axis thereof for introducing a dose of powder into the inhalation channel, the dosing unit having a central shaft co-axial with the central axis of the inhaler body, the central shaft having an end face with a spiral groove or protrusion and the indicating wheel having a toothed periphery for engaging the spiral groove or protrusion.
In a preferred embodiment the indicating wheel is rotatably supported by the storage unit and the divider is constructed as a substantially flat member so as to minimize the risk of powder accumulting on the upper surface thereof.
Preferably, the inhaler body further comprises an air inlet in a side wall thereof, the air inlet allowing air to be drawn to the dosing unit and through the inhalation channel. In a preferred embodiment the air inlet is provided in a recess in the inhaler body.
In another aspect, the invention provides a method of constructing an inhaler for administering powder by inhalation, comprising the steps of: providing as a single integral unit of an opaque material an inhaler body with a divider substantially closing one end thereof; fitting an indicating wheel in the inhaler body in such a manner as to be rotatable in a diametrical plane containing the central axis thereof, the inhaler body having an opening through which at least part of the indicating wheel is visible and the indicating wheel providing an indication as to the usage of the inhaler; and fitting a storage unit comprising a storage chamber for storing powder for inhalation in the inhaler body, the storage unit being formed of a transparent material and including a portion which substantially fills the opening.
Medicaments suitable for administration by the powder inhaler of the present invention are any which may be delivered by inhalation and include for example xcex22-adrenoreceptor agonists, for example, salbutamol, terbutaline, rimiterol, fenoterol, reproterol, adrenaline, pirbuterol, isoprenaline, orciprenaline, bitolterol, salmeterol, formoterol, clenbuterol, procaterol, broxaterol, picumeterol, TA-2005, mabuterol and the like, and their pharmacologically acceptable esters and salts; anticholinergic bronchodilators, for example, ipratropium bromide and the like; glucocorticosteroids, for example, beclomethasone, fluticasone, budesonide, tipredane, dexamethasone, betamethasone, fluocinolone, triamcinolone acetonide, mometasone and the like, and their pharmacologically acceptable esters and salts; antiallergic medicaments, for example, sodium cromoglycate and nedocromil sodium; expectorants; mucolytics; antihistamines; cyclooxygenase inhibitors; leukotriene synthesis inhibitors; leukotriene antagonists; phospholipase-A2 (PLA2) inhibitors; platelet aggregating factor (PAF) antagonists and prophylactics of asthma; antiarrhythmic medicaments; tranquilisers; cardiac glycosides; hormones; antihypertensive medicaments; antidiabetic medicaments; antiparasitic medicaments; anticancer medicaments; sedatives; analgesic medicaments; antibiotics; antirheumatic medicaments; immunotherapies; antifungal medicaments; antihypotension medicaments; vaccines; antiviral medicaments; proteins; polypeptides and peptides, for example, peptide hormones and growth factors; polypeptide vaccines; enzymes; endorphines; lipoproteins and polypeptides involved in the blood coagulation cascade; vitamins; and others, for example, cell surface receptor blockers, antioxidants, free radical scavengers and organic salts of N,Nxe2x80x2-diacetylcystine.